This is my first blackjack grow. I stared 6 plants from seed in rockwool, transferred them to my hydro/areo system. they were fine for a few days and are still growing fine with good color but the edges of most of the leaves are cupping upward creating like a bowl. there are other plants of different varieties started from clones in the same system that are not having any issues, just the blackjack. ph is at 5.99 light is an 8 bulb t5 bank.
yes its mostly on the top leaves, the grow room has been around 80 degrees and trying to keep RH down around 55-65% the temp and humidity have spiked a couple times in the last few days to 85 deg and 85% rh the T5 lights are a good 16 inches or so above the younger blackjack. and only like 4 inches above the older church and kush. my growing supply store guy looked it up and said they may be low phosphorus so i gave them a shot of bloom last night, dosnt appear to have helped. I did notice while checkin ph today that the nute solution is at 80 degrees, could that be the problem?
No the solution temp shouldn't be an issue. It looks like the leaf cupping is most likely from one or more heat spikes.
Are you using any calmag. I was reading about cupping earlier and it sounds like it is mag problem. Are there any brown spots?
no brown spots and yes i use mag amp from cutting edge at a rate of 2 ml per gallon. Im pretty sure it is due to the temp spikes. im going to put in an air conditioner Thanks much to both of you that responded.